What is your RAM allocation in Photoshop and your Cache size in Bridge?
75% in ps, and in bridge the slider is about 2/5ths between 10,000 and 500,000 items, lol.
I shouldn't think that should matter at all, though, because in this instance I used the standalone Adobe DNG Converter program, not Bridge or Photoshop.
I want to try to reproduce this problem, a few questions...
Which version of the DNG converter did you use (the latest is 5.5)?
What camera produced the NEFs?
What NEF settings did you use, if any, compressed, uncompressed, 14-bit, etc.?
What DNG conversion settings did you use?
Did the NEFs already have settings (XMP sidecar files?). If you did have settings, what kind of settings, just basic adjustments, or did the settings also include localized corrections, spot heals, etc.?
dng converter 22.214.171.124
nikon d700, d3
not sure of the nef settings
lossless compressed dng, no embed, preserve raw image, large preview
existing xmp with moderate adjustments and spot heals etc.
just over a thousand images, didnt get past 43
I've so far been unable to reproduce your problem.
Questions: What happens if you convert the same batch of files but with no adjustments?
If the problem only occurs when the files have adjustments, please provide me with some sample files (I can send you instructions).